Friction Stir Welded Magnesium Alloy Research Articles

Effect of notch location on fatigue crack growth behavior for inhomogeneous material domains in friction stir welded magnesium alloy

The fatigue crack growth behavior of friction stir welded joints of AZ31 Mg alloy is investigated for three different notch locations. The extended finite element method based simulation is developed to capture the effect of stir zone on fatigue crack growth behavior. The notch locations with asymmetric material domain experience an asymmetric stress field, which leads to crack path deviation from the orthogonal direction to the applied force. This leads to a longer crack path. The near-tip stress field from the simulation enhances the understanding of unusual crack path. The experimental results including crack path trajectories from experiments compare well against the numerical predictions.

Challenges on friction stir welding of magnesium alloys in automotives

The most important advancement in metal joining during the last few decades is the Friction Stir Welding (FSW) process. When welding magnesium or light weight alloys, FSW offers several benefits. Due to its advantages in lightweight construction, friction stir welding of magnesium alloys are widely used in the aerospace, marine, transport sector, particularly in automobiles and trucks, where they may significantly increase fuel economy and reduce emissions. Research and development in the area of FSW and related technologies have recently been advancing quickly on a global scale. The fundamentals of friction stir welding and a number of characteristics of friction stir welded magnesium alloys have been discussed in this article. Furthermore, this review reports the summary of the present status of friction stir welding of magnesium alloys with automotive applications. In addition to that, the properties, structure, flammability and wear behavior of magnesium alloys have been described.

Microstructure, mechanical and corrosion behaviours in friction stir welding of dissimilar magnesium alloys

AbstractUsing magnesium alloys reduce the weight of a vehicle considerably, but the available fusion welding methods impose restrictions on the fabrication of magnesium alloy components. Friction stir welding is an efficient method to weld magnesium alloys, but due to extreme plasticization and stirring of materials, the microstructures are transformed. Similar to other alloys, friction stir welded magnesium alloys are also susceptible to corrosion. In the present work, dissimilar AZ31 and AZ91 Mg alloys were friction stir welded at varying welding conditions. The variable presence of small cracks with a high amount of oxide, and microstructural and textural differences result in varying joint strength, that is, joint efficiency, which has a maximum value of approximately 90% of a stronger base material. The maximum corrosion potential obtained in welded zones is approximately equal to a base material that conveys similar electrochemical behaviour. The minimum corrosion rate of 0.22 mm/year is observed in the sample welded at 700 rpm tool rotational speed, 30 mm/min welding speed and 18 mm shoulder diameter.

Artificial intelligence algorithms for prediction of the ultimate tensile strength of the friction stir welded magnesium alloys

Artificial intelligence algorithms for prediction of the ultimate tensile strength of the friction stir welded magnesium alloys

Review: Corrosion behavior of friction stir welded magnesium alloys

Review: Corrosion behavior of friction stir welded magnesium alloys

Data driven knowledge summarization of friction stir welded magnesium alloys literature by using natural language processing algorithms

Data driven knowledge summarization of friction stir welded magnesium alloys literature by using natural language processing algorithms

Strain hardening behaviour of friction stir welded magnesium alloy

The present investigation is used to analyze the strain hardening behaviour of friction stir welded magnesium alloy. Hot rolling process is involved in strain hardening of magnesium alloy. The alloy is operated at above the recrystallization temperature. Titanium zirconium molybdenum (TZM) and cubic boron nitride (CBN) tool tip is considered for friction stir welding process (FSW). Vicker hardness tester is used to evaluate the hardness after strain hardening process. In FSW process, tool rotational speed, welding speed and feed is considered to evaluate the hardness. Hardness is measured and compared with tool tip materials. The optimal hardness is attained by taguchi method. Surface plot is used to analyze the correlation between input and output constrains. Liquid penetrant inspection is utilized to found the defects in welded joints. Optimal hardness was achieved at tool rotational speed of 1500 rpm, welding speed of 50 mm/min and feed of 15 mm/min.

Effect of Shot Peening on the Ballistic Performance of Friction Stir Welded Magnesium Alloy (AZ31B) Joints

Effect of Shot Peening on the Ballistic Performance of Friction Stir Welded Magnesium Alloy (AZ31B) Joints

Microstructural, Thermal and Corrosion Characterization of Friction Stir Welded Magnesium Alloys

The requirement for structural materials with demanding properties is always a major concern among automotive researchers. Magnesium alloys possess the required properties. In this work magnesium alloys, AZ31B and AZ91B were joined by friction stir welding. The influence of process parameters on the weld properties has been studied. The process parameters were tool rotational speed, welding speed, tilt angle. Three different combinations AZ31B-AZ91B, AZ31B-AZ31B and AZ91B-AZ91B were friction stir welded. Non-destructive tests have been performed on the welded joints as the primary analysis. After mechanical testing, optical microscopic examination comprising of macrostructure analysis, microstructure analysis and SEM analysis were carried out on selected specimens and the results are formulated. The corrosion behavior of Mg alloys has been tested using a salt spray test. The thermal behavior was studied using thermogravimetric and differential thermal analysis. The joints were friction stir welded with maximum efficiency where grain refinement was observed in the weld microstructure of dissimilar alloys and the elongated grains was recrystallized. This paper primarily focuses on the microstructural aspects, corrosion performances and TG/DTA analysis.

Experimental investigation and optimization of quality characteristics during friction stir welding of Al- and Zn-based magnesium alloy using artificial intelligence

Friction stir welding is successfully used to weld different wrought magnesium alloys. This work investigated the mechanical and microstructural behavior of the friction stir-welded AZ31B magnesium alloy. The experiments were conducted as per experimental runs designed by response surface methodology. An artificial neural network model was developed to produce a relationship between process variables (tool rotational speed, welding speed, and tool shoulder diameter) and characteristics of the friction stir-welded joints (tensile strength, percentage elongation, impact strength, microhardness, and grain size). The acceptable range of statistical parameters validated the adequacy of the model. The multi-objective optimization technique, genetic algorithm was used to obtain a set of Pareto optimal solutions. The best-compromised optimum solution for maximum tensile strength (164.2 MPa), percentage elongation (8%) impact strength (3.5 J), microhardness (85 Hv), and minimum grain size (13.1 μm) was validated by confirmation test with <3 percent absolute error percentage. The fractographical analysis has been performed and dimples and torn edges observed in fracture zones.

Review Paper on Hardness Improvement Studies on Friction Stir Welded Alloys

Magnesium amalgam one of the significant crude material utilized in these businesses because of its light weight, great warm conductivity and so on. Additionally, Friction Stirs welding is the joining process that is being utilized in these businesses as it is a strong state joining process. A friction stir welding is widely used in automobile and aerospace sectors for smooth finishing and strength of materials, there is still scoped to take up further research in this area. In this paper, it is discussed the improvement method of friction stir welded magnesium alloy plates.

Effect of heat treatment conditions on ballistic behaviour of various zones of friction stir welded magnesium alloy joints

Abstract Ballistic behaviour of different zones of post-weld heat-treated (PWHT) magnesium alloy (AZ31B) target against 7.62 mm × 39 mm armour-piercing (AP) projectile with a striking velocity of (430±20) m/s was determined. Magnesium alloy (AZ31B) welded joints were prepared by using friction stir welding (FSW) process and subjected to different heat treatment conditions. The microhardness values of non-heat-treated and heat-treated FSW joints were investigated. The results indicated that PWHT process (250 °C, 1 h) has improved the microhardness of heat-treated FSW joints. Scanning electron microscope (SEM) microstructure showed that heat treatment has caused the formation of fine α-Mg grains and tiny precipitates and made the dissolution of β-Mg17Al12 phase into the Mg matrix. The ballistic behaviour of PWHT zones was estimated by measuring the depth of penetration (DOP) of the projectile. Lower DOP value was observed for the base metal zone (BMZ) of a heat-treated welded joint. Post ballistic SEM examinations on the cross-section of all three zones of crater region showed the formation of adiabatic shear band (ASB).

Improved corrosion resistance of friction stir welded magnesium alloy with micro-arc oxidation/electroless plating duplex coating

In this study, the corrosion behavior of duplex coating on friction stir welded AZ31 alloy was investigated by a series of characterization methods and electrochemical tests. The duplex coating consisted of a micro-arc oxidation (MAO) intermediate layer and an electroless nickel (EN) top layer was applied to the friction stir welding (FSW) joint to enhance its corrosion resistance. The experimental results exhibited that the heterogeneous microstructure in the different zones of the FSW joint caused inhomogeneous susceptibilities to local corrosion. The coarse second phase in the heat-affected zone (HAZ) decreased the corrosion resistance. Although the microstructure differed in the different zones, the morphology of the duplex coating is no significant difference in different zones of the FSW joint. The dense EN top layer and porous MAO intermediate layer were bonded by mechanical interlocking because parts of the EN layer were embedded in the micro-pores of the MAO layer. After depositing the duplex coating, the corrosion potential was raised, and the corrosion current density was reduced. Therefore, the duplex coating provided the FSW joint with improved corrosion resistance. The protection mechanism of the duplex coating against corrosion is depicted in schematic diagrams that explain the corrosion behavior and corrosion mechanism.

Tensile Strength Comparison of Friction Stir Welded Magnesium Alloys Using ASTM / ASME Standards

Tensile Strength Comparison of Friction Stir Welded Magnesium Alloys Using ASTM / ASME Standards

Review Paper on Hardness Improvement Studies on Friction Stir Welded Alloys

Magnesium amalgam one of the significant crude material utilized in these businesses because of its light weight, great warm conductivity and so on. Additionally, Friction Stirs welding is the joining process that is being utilized in these businesses as it is a strong state joining process. A friction stir welding is widely used in automobile and aerospace sectors for smooth finishing and strength of materials, there is still scoped to take up further research in this area. In this paper, it is discussed the improvement method of friction stir welded magnesium alloy plates.

Effect of texture and banded structure on the crack initiation mechanism of a friction stir welded magnesium alloy joint in very high cycle fatigue regime

Friction stir welding (FSW) produces heterogeneous microstructure in nugget zone of its joint, which should affect the fatigue responses. This work revealed the unique texture and banded structure of the Mg-FSW joint and their decisive roles on crack initiation behaviors. At higher stress levels, failures occur along the AS NZ/TMAZ boundary (AS: advancing side, NZ: nugget zone, TMAZ: thermo-mechanically affected zone) due to the inhomogeneous deformations near the boundary. Severe plastic deformations concentrate in the softer layers of banded structure. However, at lower stress levels, plastic deformations become weak and localized, but accumulate in the alternate layers of banded structure simultaneously due to the same soft texture orientation, and induce random failures in banded structure. The failure mechanisms are verified by semi-quantitative mechanical models.

Effect of Ca addition on the microstructure and the mechanical properties of asymmetric double-sided friction stir welded AZ61 magnesium alloy

Abstract The effects of 2% Ca addition on the microstructure and the mechanical properties of the asymmetric double-sided friction stir welded magnesium alloy AZ61 were investigated. Compared to the Ca-free AZ61magnesium alloy, the addition of 2% Ca significantly refines the grains in the stir zone after welding. Due to the existence of thermally stable Al2Ca particles, there is no noticeable change in the grain size in the stir zone regardless of the welding heat input. The electron backscattered diffraction analysis at the center of the stir zone confirmed the significant deterioration of the (0001) texture strength from the addition of 2% Ca. The tensile test of the joint suggested that the addition of 2% Ca provides stable tensile properties to the joint regardless of the welding parameters. The critical (0001) texture strength that determines the ultimate tensile strength decreased from 20 to 15 by the Ca addition. The addition of Ca enhanced the deterioration of the plastic elongation when the (0001) texture strength increased.

Microstructural analysis of friction stir welded Mg AZ31 alloy

Magnesium alloys are the lightest of all structural metals and are in great demand in various automotive and aerospace industry. The current research work focusses on evaluating the effects of input process parameters on the metallurgical properties of friction stir welded magnesium alloys. The variable input parameters chosen are tool rpm, travel speed and the plunge depth. Microstructural studies revealed three distinct zones in the welded specimen, viz: stir zone also known as the weld nugget, thermo mechanical affected zone and the unaffected base material. Large sized grains were observed at the top surface of the welded specimens due to more heat input at the top. The microhardness of the workpiece was measured in the traverse direction and maximum hardness observed in the stir zone is about 16% higher than the parent material.

Analysis of Weak Zones in Friction Stir Welded Magnesium Alloys from the Viewpoint of Local Texture: A Short Review

Friction stir welding (FSW) is a promising approach for the joining of magnesium alloys. Although many Mg alloys have been successfully joined by FSW, it is far from industrial applications due to the texture variation and low mechanical properties. This short review deals with the fundamental understanding of weak zones from the viewpoint of texture analysis in FSW Mg alloys, especially for butt welding. Firstly, a brief review of the microstructure and mechanical properties of FSW Mg alloys is presented. Secondly, microstructure and texture evolutions in weak zones are analyzed and discussed based on electron backscatter diffraction data and Schmid factors. Then, how to change the texture and strengthen the weak zones is also presented. Finally, the review concludes with some future challenges and research directions related to the texture in FSW Mg alloys. The purpose of the paper is to provide a basic understanding on the location of weak zones as well as the weak factors related to texture to improve the mechanical properties and promote the industrial applications of FSW Mg alloys.

Review on friction stir welding of magnesium alloys

Abstract Friction Stir Welding (FSW) is considered to be the most significant development in metal joining in last two decades. FSW has many advantages when welding magnesium or lightweight alloys. The Friction stir welding of magnesium alloy has many potential applications in major industries i.e. land transportation, aerospace, railway, shipbuilding and marine, construction, and many other industrial applications. Even magnesium alloys have been used in industrial equipment of nuclear energy as magnesium alloys have low tendency to absorb neutrons, sufficient resistance to carbon dioxide and excellent thermal conductivity. Recently, the research and development in FSW field and associated technologies have been developing rapidly worldwide. In this review article, the basic principle of friction stir welding and several aspects of friction stir welded magnesium alloys have been described. The current state of friction stir welding of magnesium alloys is summarized. In spite of this, much remains to be learned about the process and opportunities for further research are identified.